I mean: Which laws govern US agencies' domestic propaganda activities?
By now I've read about the Foreign Agents Registration Act (1938) that insures that the American public and its law makers know the source of information (propaganda) intended to sway public opinion. I've also read about the Smith-Mundt Act (1948) and its 1972 amendment, which places certain restrictions on only the USIA from engaging in domestic propaganda. So far I've not been able to find any law that prohibits for example the CIA to engage in domestic propaganda activities. (The National Security Act of 1947 simply bans the CIA from operating within the US, so that would include spreading propaganda.)